MimeTypeGuesser.php

class MimeTypeGuesser extends BaseMimeTypeGuesser
{
    /**
     * Constructor overridden since it's private in the base class :/
     */
    public function __construct()
    {
        if (FileBinaryMimeTypeGuesser::isSupported()) {
            $this->register(new FileBinaryMimeTypeGuesser());
        }

        if (FileinfoMimeTypeGuesser::isSupported()) {
            $this->register(new FileinfoMimeTypeGuesser());
        }

        // register our custom mime type
        $this->register(new MSFormatMimeTypeGuesser());
    }
    /**
     * Returns the mime type for a file
     *
     * @param \Symfony\Component\HttpFoundation\File\File $file
     * @return string
     */
    public function getMimeType(File $file)
    {
        return $this->guess($file->getPathname());
    }
}